But judging by what’s come to light so far, fears over whiplash-like changes to US foreign and defence policy norms are misplaced. Indications from both Trump’s personal history and his administration’s behaviour both suggest that on balance, his country’s attitude to nuclear weapons and international alliances will be marked by continuity more than change.

For starters, it pays to look at the things Trump has actually said about all this. An excellent study by Jeffrey Michaels and Heather Williams (published in Contemporary Security Policy) collected and analysed many, if not all, of Trump’s public statements on nuclear weapons during the 2016 campaign – and found that many of the attitudes he expressed are consistent with those of previous presidents.

Looked at from the right angle, Trump’s nuclear position is less an unknown quantity and more a Frankenstein-esque assemblage of familiar Republican worldviews. His apparent conviction that so-called “rogue states” such as North Korea should not get their hands on nuclear weapons is firmly in the tradition of George W Bush. Scepticism about costs aside, Trump also seems to share Ronald Reagan’s faith in missile defence, as well as his fears about the consequences of nuclear war.

Trump also openly embraces the virtues of nuclear superiority – the idea that states can gain coercive leverage over their adversaries by having more or better nuclear weapons. That puts him in the mould of Richard Nixon and Dwight Eisenhower. Indeed, his administration is using the spectre of nuclear proliferation in East Asia to put pressure on China, much as Nixon and Kissinger did as part of their overture to Beijing in the early 1970s.

Besides, the administration is likely to take its nuclear advice from relatively established characters. Two such figures are Keith Payne and Christopher Ford: far from being outsiders, they are very established policy thinkers on nuclear modernisation, nonproliferation, and arms control. Both served under George W Bush; Payne was a major influence on the 2002 Nuclear Posture Review, while Ford crafted the Bush administration’s nonproliferation policy.

No country is an island

There’s been rather more hand-wringing when it comes to Trump’s dim view of international alliances. His past statements on defence burden-sharing do indeed imply a break from even post-9/11 Republican orthodoxy. Nevertheless, there are plenty of reasons to expect more continuity than change.

After all, the point of its multilateral setup is partly to put a check on the US, by far the most powerful member state, which has the muscle to act arbitrarily and shortsightedly. The NATO structure enables weaker allies to form diplomatic coalitions against undesirable US initiatives, exerting a collective moderating influence if they fear that their interests would be jeopardised – by an ill-thought-through rapprochement with Russia, say.

Alliances are useful even for pursuing détente with a major power, and they offer leverage during negotiations, and insurance if a deal falls apart. Should the Trump administration fully embrace great power politics, it will need allies with it all the way; if it wants to take a dramatically more hawkish line on China, for instance, it’ll need to maintain its strong ties with East Asian partners such as Japan and South Korea.

The same principle holds true as the administration sets about dealing with Russia. While the possibility of greatly improved Moscow-Washington relations seems more distant since the US’s air strikes on Syrian government targets, a stronger, more cohesive NATO would certainly improve Trump’s bargaining position with Putin if and when American and Russian interests start to clash.

None of these points are cause for complacent optimism about the Trump administration’s foreign policy. Its State Department is badly understaffed by choice; many of its positions seem unclear or subject to sudden change, with Trump himself sometimes openly contradicting his own team. And of course, the spectre of further scandals about the Trump team’s interactions with the Kremlin looks set to overshadow the administration for some time. But anyone who thinks the US has suddenly slipped its moorings altogether is missing the point.